1. Field of the Invention
This invention relates to a part to be attached and/or fixed to a printed wiring board by soldering.
2. Description of Related Art
There is known a soldering method in which electronic parts or small mechanisms are attached to a printed wiring board and then the copper foil surface of the printed wiring board is dipped in melting solder in a tank of a solder dipping device, thereby completing electrical connection of the electronic parts and/or attachment of the mechanisms to the copper foil portion by a single operation. The electronic parts to be attached to the printed wiring board generally have terminals of small heat capacity, and hence the terminals and the copper foil patterns can be easily soldered by dipping the printed wiring board in melting solder in a soldering device.
On the other hand, a heat radiating plate used for heat radiation of a three-terminal regulator and the like is small in size and is positioned adjacent to an electric circuit, and hence such a heat radiating plate is frequently used in a manner attached to the printed wiring board. In order to prevent that the small heat regulating plate damages the copper foil pattern to which a three-terminal regulator is attached when the external force is applied to the heat radiating plate, the legs of the heat radiating plate are soldered to the copper lands of the printed wiring board.
Since such a heat radiating plate has large heat capacity, the legs thereof cannot be soldered to the printed wiring board with sufficient reliability by simply dipping the legs in the melting solder in the soldering device. In addition, if a soldering iron is to be used, a special design in consideration of the soldering reliability is needed. In this view, various proposals have already been made.
For example, Japanese Laid-Open Utility Model application No. 5-95092 discloses the attachment manner of a heat radiating plate that offers improved soldering reliability when the soldering iron is used. This heat radiating plate is shown in FIG. 4. As shown, the heat radiating plate 2 has engaging portions 2a which are inserted into the attachment holes 1a of the printed wiring board 1, and small holes 2b are formed on the heat radiating plate 2 near the engaging portions 2a. With the heat radiating plate 2 thus configured, when the engaging portions 2a are heated by the soldering iron, the small holes 2b prevent the heat applied to the engaging portions 2a from radiating via the heat radiating plate, and thus the soldering operation can be easily performed.
The manner of attaching the heat radiating plate 2 described above improves the reliability of soldering in the case of soldering using the soldering iron However, in case of using the solder dipping device using nolead solder of high melting point, the heat applied to the engaging portion 2a propagates to the heat radiating plate 2 from the bottom areas leftward and rightward of the small hole 2b. As a result, the temperature of the nolead solder decreases, and hence soldering bridge takes place at the engaging portion 2a or the solder deforms to be ball-like shape, thereby deteriorating the reliability of soldering,
It is an object of the present invention to provide a part that can be reliably soldered to a printed wiring board even by a solder dipping device which uses nolead solder having high melting point.
According to one aspect of the present invention, there is provided a part including: a body unit, and one or more leg formed on the body unit, wherein one or more slit is formed on the body unit adjacent to the leg.
In accordance with the part thus configured, the legs are inserted to insert holes of a printed wiring board or the like and soldered thereto. Since the slit is formed adjacent to the leg, the heat applied to the leg for the soldering is not radiated by the body unit by virtue of the slit. Therefore, the part can be reliably attached to the printed wiring board or the like.
In an embodiment, the slit may be formed on the body unit such that a longitudinal direction of the slit coincides a longitudinal direction of the leg, and a length of the slit prescribes a length of the leg. The slit may be formed such as to position a tip of the leg remotely from the body unit, and thus the slit decreases radiation of heat applied to the leg by the body unit.
Preferably, the body unit may include a main plate and a pair of side plate connected to the main plate, and the main plate and the side plate may be formed in a U-shape in section. By this, the part can be stably attached to the printed wiring board even if any external force is applied.
Further, the body unit may include one or more attachment hole to which electronic part is attached. By this attachment hole, necessary electronic parts can be attached to the part.
The nature, utility, and further features of this invention will be more clearly apparent from the following detailed description with respect to preferred embodiment of the invention when read in conjunction with the accompanying drawings briefly described below.